Sleep and your gut

How does sleep affect your stomach? Does the gut ever sleep? Let's first talk about the sleep cycle, and how your gut moves as a result of it.

Does the gut sleep?

Most of us humans are diurnal, meaning active in the daytime and asleep at night, and the force behind establishing this schedule is our circadian rhythm. One of my favorite writers on the topic describes it as an "internal 24-hour clock within your brain that communicates a rhythmic signal to every other region of your brain and every organ in your body." Unsurprisingly, the gut is an important receiver of that signal. Your gut is constantly on the move, but it is smart enough to know when to prioritize its activity (a future post will be sure to explore the mind-gut axis).

When you go to sleep, so does your gut. Overnight the gut will have slow sweeping movements, but in terms of forward momentum (through contractions, peristalsis, etc.) the GI tract is relatively quiet while you sleep. When you wake up, there is a huge spike in the activity of your gut - specifically your colon - that doctors call a "wake response." One way to think of this wake response is that your gut wants to clear the way and prepare itself for the incoming breakfast food headed its way.

This spike in the movement of your colon often leads to a morning poop. If you're someone who regularly poops as soon as they wake up, you have your circadian rhythm and a strong mind-gut connection to thank! For those coffee drinkers out there, caffeine can act as a powerful stimulant of the colon, so using it to hijack the morning spike in colonic activity can be a good way to stimulate a morning poop.

How does sleep deprivation affect the gut?

In the short-term, shifting your circadian rhythm can throw your wake response off. In fact it's not uncommon for your bowel schedule to get completely altered when traveling abroad, and at least part of that is due to upending your circadian rhythm. There has been fascinating research looking at the long-term effect of sleep deprivation on your gut. Put simply, the less you sleep the more likely you are to eat, and your metabolism is less efficient in a sleep deprived state. Even a single night of sleep deprivation can cause hormonal changes that mimic pre-diabetes!

Does staying awake longer burn more calories?

You would think that staying awake would lead to burning more calories, but unfortunately that's not the case. Sleeping is actually a metabolically active state, and is important for maintaining your metabolism over time. Poor sleep can even alter your gut microbiome, fostering an environment for bad bacteria (read our post explaining the microbiome). There is a U-shaped curve with sleep and weight gain: getting less than 6 hours or more than 10 hours is associated with gaining weight.

It's no coincidence that as obesity has exponentially increased, our average hours of sleep have decreased. Making no other changes to your diet, even just routinely getting 8 hours each night has been shown to help with weight loss. Bottom line: if you're trying to lose weight, do yourself a favor and get some sleep!